<!DOCTYPE html>
<!-- 文档配置：语言 -->
<html lang="en">
    <!-- 浏览器窗口配置 -->
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- 样式 -->
        <style>
            button{
                background-color: yellow;
                font-size: 18;
            }
        </style>
</head>
<body>
    <!-- 结构 -->
     <button>许个愿吧</button>
     <!-- 行为 -->
      <script>
        document.querySelector('button').onclick=()=>{
            alert('666')
        }
      </script>
</body>
</html>